A 3DP synchronous micro-rolling printing method, application and printer

Abstract

The present invention proposes a 3DP synchronous micro-rolling printing method, application and printer, including cutting a three-dimensional casting model to obtain a plurality of printing layers, and using a printer to sequentially lay and compact material powder, spray adhesive, and compact and level the printing layers to form a casting blank, and then solidify and dry the casting blank to obtain the casting blank; as the printing layer is pressurized, the rolling pressure will be increased synchronously, which can effectively improve the density of the blank, and the shrinkage rate of the blank is small when the blank is solidified and dried, and the obtained casting has good strength, porosity and surface roughness; at the same time, the laying, compaction and adhesive spraying of material powder are carried out synchronously, and the rolling of the printing layer and the nozzle resetting process are carried out synchronously, which can effectively improve the printing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a 3DP synchronous micro-rolling printing method, application and printer. Background Art

[0002] At present, microjet bonding technology (3DP) is a new additive manufacturing method based on powder materials. The forming process of this process is fully controlled by a computer, and no special fixtures, tools and molds are required. Compared with traditional processing and forming processes, it has the advantages of integrated design and manufacturing, highly flexible and rapid forming process, low labor intensity, high material utilization rate, and easy operation. Compared with selective laser sintering (SLS), which is also a rapid manufacturing method, 3DP uses a nozzle to spray a binder instead of laser sintering, which has outstanding advantages such as small equipment investment, low operating cost, and good environmental adaptability. Therefore, microjet bonding forming technology is very suitable for rapid forming of castings.

[0003] The invention patent application with the existing application publication number CN112404456A proposes a metal powder forming method. The method forms a printed shell model according to the structure of the workpiece, cuts the printed shell model to form a corresponding contour to be printed, and wraps the metal powder inside the contour through the printed contour, selectively performs debonding treatment, and then performs sintering and heat treatment to finally obtain a complete metal workpiece.

[0004] In the above technical scheme, laser hot-melt metal powder is used for printing, or metal powder is bonded with adhesive for printing. When printing and molding is performed by spraying adhesive, the density of the prepared mold is low, which leads to excessive shrinkage of the embryo during drying, which is not conducive to the molding of the finished product; and after molding, there are problems such as low strength of the finished product, poor pouring performance, and high porosity. After being used for casting, the molded parts are prone to typical problems such as many surface pores, surface slag inclusions, and poor precision. These problems significantly reduce the yield rate of 3DP molds, shells, and cores, seriously affect the dimensional accuracy and surface quality of castings, and even cause the problem of serious sand sticking to castings. Summary of the invention

[0005] In view of this, the present invention proposes a 3DP synchronous micro-rolling printing method, application and printer that can improve the structural performance of the casting mold, so as to solve the problem that the structural performance and application performance of the finished product obtained by printing the casting mold using a binder are poor.

[0006] The technical solution of the present invention is achieved in this way:

[0007] In one aspect, the present invention provides a method for 3DP synchronous micro-rolling printing, comprising the following steps:

[0008] S1. According to the size of the mold, a three-dimensional model is established through a three-dimensional modeling software, and the three-dimensional model is sliced ​​along the Z-axis direction using a slicing software to obtain a number of printing layers, and processing instructions are generated for all printing layers, and printing parameters and rolling mechanism parameters are set at the same time;

[0009] S2, laying a layer of modeling material powder in the powder bed of the printer, and compacting the modeling material powder along the XY plane with a roller mechanism;

[0010] S3, during the compaction process, according to the processing instructions of the printing layer, the nozzle is used to synchronously spray the binder on the selected area above the modeling material powder layer, so that the modeling material powder layer is bonded to form the current printing layer contour, and then the nozzle returns to the starting position;

[0011] S4, when the nozzle returns to the starting position, the rolling mechanism is used to synchronously roll the bonding forming area along the XY plane, and then the rolling mechanism returns to the starting position;

[0012] S5, the powder bed of the printer moves down one layer thickness along the Z axis direction, and the printer switches to the processing instructions for the next layer;

[0013] S6, repeating steps S2 to S5 in sequence, and increasing the rolling pressure of the rolling mechanism as the number of printed layers increases, until the casting mold body is formed;

[0014] S7, taking the embryo out of the powder bed and drying and curing it.

[0015] On the basis of the above technical solution, preferably, the modeling material powder is one of aluminum oxide, yttrium oxide, zirconium oxide, calcium oxide and silicon powder with a particle size of 50-2000 mesh.

[0016] On the basis of the above technical solution, preferably, the binder is one of phenolic resin, furan resin, silica sol and yttrium sol.

[0017] On the basis of the above technical solution, preferably, the thickness of the printed layer is 5-200 microns, and the drying temperature is 50-200°C.

[0018] On the basis of the above technical solution, preferably, in step S1, a plurality of printed layers are processed in sections according to the size of the structural strength along the Z-axis direction, and the initial value of the rolling pressure is adjusted according to the strength of the section structure.

[0019] On the basis of the above technical scheme, preferably, the rolling pressure range of the rolling mechanism is 1~2000N, the rolling pressure increases by 0.1~20N for every N layers printed, 5≤N≤20, and the rolling pressure of the rolling mechanism in the last printed layer is ≤2000N.

[0020] On the basis of the above technical solution, preferably, when the rolling mechanism rolls a print layer that is a multiple of N, the rolling pressure is increased by 0.1~20N, 5≤N≤20, and when printing a print layer that is not a multiple of N, the rolling pressure is the initial value.

[0021] On the basis of the above technical solution, preferably, when the rolling mechanism rolls a multiple of N printed layers, the rolling travel speed of the rolling mechanism in the current printed layer is reduced by 20% to 50%.

[0022] On the other hand, the 3DP synchronous micro-rolling printing method of the present invention is mainly used for the production of casting molds.

[0023] On the other hand, the present invention provides a printer applied to the above-mentioned 3DP synchronous micro-rolling printing method, which includes a first displacement mechanism, a carrier, a powder distribution mechanism, a rolling mechanism, a second displacement mechanism, a nozzle and a powder bed, wherein:

[0024] The first displacement mechanism and the second displacement mechanism are three-axis screw slides; the carrier is arranged on the first displacement mechanism;

[0025] The powder distribution mechanism, the rolling mechanism and the second displacement mechanism are each connected to a linear displacement component and are arranged in parallel on the carrier in sequence;

[0026] A nozzle is arranged on the second displacement mechanism;

[0027] The powder bed is arranged on one side of the first displacement mechanism, and the bed surface of the powder bed faces the powder distribution mechanism, the rolling mechanism and the nozzle.

[0028] The 3DP synchronous micro-rolling printing method of the present invention has the following beneficial effects compared with the prior art:

[0029] During the printing process, the material powder is rolled by a rolling mechanism, which can effectively compact the material powder and reduce the gap between the powder materials. In this way, the spraying adhesive can make the printed layer better. At the same time, since the rolling pressure will increase with the increase of the printed layer, it can effectively ensure that the embryo formed after the multi-layer stacking of the printed layer has a high density. During the drying and curing process, the density of the embryo is large, which can reduce the shrinkage rate of the casting, reduce the porosity, and effectively improve the surface roughness and bending strength. The overall structure of the printed casting embryo is compact; after the casting is dried and used for casting, the casting will have good structural strength and precision;

[0030] The material powder compaction and adhesive spraying are carried out simultaneously, and the nozzle returns to the starting position and the roller print layer is carried out simultaneously, which can effectively improve the printing efficiency and the casting production efficiency;

[0031] The molding material powder is one of aluminum oxide, yttrium oxide, zirconium oxide, calcium oxide and silicon powder with a particle size of 50-2000 meshes, and the binder is one of phenolic resin, furan resin, silica sol and yttrium sol, which is adapted to the roller pressure range, roller pressure increase range, printing layer thickness and drying temperature of the method. The combination of the above technical means can ensure the production of casting blanks with good performance;

[0032] By processing several printed layers in sections according to their structural strength and adjusting the initial value of the rolling pressure according to the strength of the sections, it is possible to avoid damage to the mold body caused by the progressive increase in rolling pressure, which is beneficial to ensuring the smooth molding of the mold and good structural strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a process flow chart of the method for 3DP synchronous micro-rolling printing of the present invention;

[0035] Figure 2 A printer structure for use with the present invention;

[0036] Figure 3 A schematic diagram of the printer and embryo coordinates used in the present invention;

[0037] Figure 4 This is a schematic diagram of the mold cutting and printing layer structure;

[0038] Figure 5 It is a schematic diagram of the structure of the mold printing layer;

[0039] In the figure: a first displacement mechanism 100, a carrier 200, a powder distribution mechanism 300, a rolling mechanism 400, a second displacement mechanism 500, a nozzle 600, a powder bed 700, and an embryo S. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The 3DP synchronous micro-rolling printing method of the present invention can be applied to the printing and molding of various castings, thereby being used as castings for gears, turbine blades, etc.

[0042] In the printing process, a 3D printer is needed, such as Figure 2 The printer shown in FIG. 1 includes a first displacement mechanism 100, a carrier 200, a powder distribution mechanism 300, a rolling mechanism 400, a second displacement mechanism 500, a nozzle 600 and a powder bed 700. The specific displacement coordinates are shown in FIG. Figure 2 and Figure 3 shown.

[0043] In the above printer, the first displacement mechanism 100 and the second displacement mechanism 500 adopt a multi-degree-of-freedom driving mechanism, such as a three-axis screw slide, so that it has the function of displacement along the X-axis, Y-axis and Z-axis. The carrier 200 is installed on the first displacement mechanism 100, the powder distribution mechanism 300, the rolling mechanism 400 and the second displacement mechanism 500 are arranged in parallel on the carrier 200, and the nozzle 600 is installed on the second displacement mechanism 500. In this way, the first displacement mechanism 100 can drive the carrier 200, the powder distribution mechanism 300, the rolling mechanism 400, the second displacement mechanism 500 and the nozzle 600 to perform three-axis displacement, and the second displacement mechanism 500 can drive the nozzle 600 to perform three-axis displacement. At the same time, preferably, the powder distribution mechanism 300, the rolling mechanism 400 and the nozzle 600 have a separate telescopic function, and specifically one of an electric push rod or a cylinder can be used to enable the powder distribution mechanism 300, the rolling mechanism 400 and the nozzle 600 to adjust their positions on the Z axis separately. At the same time, a powder bed 700 with a lifting function is set up, which corresponds to the powder distribution mechanism 300, the rolling mechanism 400 and the nozzle 600. The area of ​​the powder bed 700 should cover the displacement range of the first displacement mechanism 100 and the second displacement mechanism 500.

[0044] In the above content, the powder distribution mechanism 300, the rolling mechanism 400 and the nozzle 600 have separate telescopic functions, so that they can adjust their distance from the powder bed 700 separately. They are close to the powder bed 700 only when working, so as to avoid the interference between the above components and the embryo S being printed when the first displacement mechanism 100 moves. The distance from the powder bed 700 can be adaptively adjusted during printing. The telescopic function can be achieved by some linear displacement components, such as electric push rods or cylinders, among which the powder distribution mechanism 300 can be driven by a cylinder. Since the rolling mechanism 400 needs to adjust the pressure, and the distance between the nozzle 600 and the powder bed has a high influence on the adhesive injection molding, the rolling mechanism 400 and the nozzle 600 are preferably driven by a screw rod to accurately control the displacement stroke.

[0045] During the printing process, the following steps need to be performed:

[0046] First, prepare the raw materials, which may be aluminum oxide, yttrium oxide, zirconium oxide, calcium oxide or silicon powder with a particle size of 50-2000 mesh as the material powder for the casting, and may be phenolic resin, furan resin, silica sol or yttrium sol as the adhesive. The adhesive is used to bond the material powder to form the embryonic body of the casting.

[0047] Execute step S1: according to the size of the mold, establish its three-dimensional model through three-dimensional modeling software, slice the three-dimensional model along the Z-axis direction using slicing software to obtain a number of printing layers, and generate processing instructions for all printing layers, and set printing parameters and rolling mechanism parameters at the same time;

[0048] S1 specifically refers to: connecting a computer to a computer used for 3DP printing, modeling the mold through modeling software such as UG and Solidworks, then starting the Easy3Dprint software, importing the 3D model data of the mold to be printed into the software, and slicing the 3D model of the mold along the Z axis. The layered model is as follows: Figure 4 As shown, the processing instructions for layered slicing are then calculated, each layered slicing is a printing layer, and the printing parameters and rolling parameters are set according to the density of the target casting and the properties of the molding material, where the printing parameters include printing speed, printing direction and other resins, and the rolling parameters include rolling speed, rolling pressure and other parameters.

[0049] Executing step S2: laying a layer of modeling material powder in the powder bed of the printer, and compacting the modeling material powder along the XY plane with a roller mechanism;

[0050] S2 specifically means: first, the first displacement mechanism 100 adjusts the position of the carrier 200 on the Z axis, and drives the powder distribution mechanism 300 and the rolling mechanism 400 to move along the X axis through the first displacement mechanism 100, so that a layer of material powder with uniform thickness is sprayed on the powder bed 700 through the powder distribution mechanism 300, and the material powder is compacted by the rolling mechanism 400;

[0051] It should be noted that compacting the modeling material powder is to make the density of the material powder greater than the density when it is laid, which can also be called leveling. The purpose is to reduce the pores between the material powders to reduce the amount of adhesive used to save costs. Of course, it is necessary to ensure that the printed embryo contains enough adhesive, which is beneficial to improve the density of the finished product. During the compaction process, it is necessary to avoid excessive rolling pressure that may cause excessive compaction of the material powder to prevent affecting the combination of the material powder and the adhesive.

[0052] Execute step S3: during the compaction process, according to the processing instructions of the printing layer, use the nozzle to synchronously spray the binder on the selected area above the modeling material powder layer, so that the modeling material powder layer is bonded to form the current printing layer contour, and then the nozzle returns to the starting position;

[0053] S3 specifically means: the first displacement mechanism 100 drives the second displacement mechanism 500 and the nozzle 600 to move along the X-axis. At the same time, the second displacement mechanism 500 drives the nozzle 600 to move in the XY plane and spray adhesive to bond the material powder in the selected area of ​​the current printing layer to form the shape of the mold in the current printing layer. After that, the first displacement mechanism 100 is reset in the X direction. Of course, the second displacement mechanism 500 can also adjust the position of the nozzle 600 on the Z axis. The selected area is the shape of the mold in the current layer.

[0054] Execute step S4: during the process of the nozzle returning to the starting position, the printing layer is synchronously rolled along the XY plane by using a rolling mechanism, and then the rolling mechanism returns to the starting position;

[0055] S4 specifically means that the first displacement mechanism 100 drives the powder distribution mechanism 300, the rolling mechanism 400 and the nozzle 600 to reset synchronously on the X-axis. During the reset, the rolling mechanism 400 rolls the entire printing layer once, and compacts the printing area while leveling the material powder, which is beneficial to improving the density of the printed body S.

[0056] Execute step S5: the powder bed of the printer moves down one layer thickness along the Z-axis direction, and the printer switches to the processing instruction of the next layer;

[0057] S5 specifically means that after the printing of one printing layer is completed on the powder bed 700, the powder bed 700 descends along the Z axis to prepare for the printing of the next printing layer.

[0058] Execute step S6: repeat steps S2 to S5 in sequence, and increase the rolling pressure of the rolling mechanism as the number of printed layers increases until the casting blank is formed;

[0059] S6 specifically means that as the number of printed layers increases, the pressure of the rolling mechanism 400 will increase with the increase in the number of printed layers, which can ensure that the current printed layer is flattened and further improve the bonding force between the previous printed layers, which is beneficial to ensure the density of the embryo S.

[0060] Execute step S7: take the embryo out of the powder bed and perform drying and curing treatment;

[0061] After executing S7, the finished casting product can be obtained.

[0062] It can be seen from step S2 and step S4 that the rolling mechanism 400 performs two rolling operations, one for rolling the material powder and the other for rolling the entire printed layer. In the present technical solution, the compaction of the material powder and the spraying of the adhesive are carried out simultaneously, and the return of the nozzle to the starting position and the rolling of the printed layer are carried out simultaneously, thereby saving printing time. This not only ensures the strength of the embryo S and the strength of the embryo S after drying into a finished product, but also improves the printing efficiency.

[0063] In some embodiments, in step S4, the rolling pressure range of the rolling mechanism is 1~2000N, and the rolling pressure increases by 0.1~20N for every N layers printed, 5≤N≤20, and the rolling pressure of the rolling mechanism in the last printed layer is ≤2000N.

[0064] For example, N=5, the rolling pressure is 5N, and after printing every 5 layers, the rolling pressure is increased by 0.1N. Thus, the rolling pressure is 5N when printing 1-5 layers, and 5.1N when printing 6-10 layers, and so on, and the pressure can be superimposed, which can effectively ensure that the printed layers are tightly bonded. Figure 4 As shown, for some casting components that are wide at the upper and lower ends but narrow in the middle, the pressure increment setting is also conducive to testing the structural strength of the embryo S. This test refers to the test performed when the embryo S is prepared using different materials, so that engineers can know how much structural strength the embryo S of different materials has.

[0065] In some embodiments, in step S4, when the rolling mechanism rolls a print layer that is a multiple of N, the rolling pressure is increased by 0.1~20N, 5≤N≤20, and when printing a print layer that is not a multiple of N, the rolling pressure is the initial value.

[0066] Exemplarily, N=5, the rolling pressure is 5N, and the pressure increase is 2N. Thus, when printing 5, 10, 15, and other multiples of 5 layers, the rolling pressure is 7N, and when printing 1-4, 6-9, 11-14, and other layers that are not multiples of 5, the rolling pressure is restored to 5N. This is because some casting components do not require very high embryo strength, and they only need to reach the use strength after drying and curing in step S7, thereby avoiding damage to the embryo due to progressive increase in pressure.

[0067] The above two pressurizing methods can be applied according to the material powder and the type of adhesive used.

[0068] In some embodiments, in step S4, during printing, when the rolling mechanism rolls a multiple of N print layers, the rolling travel speed of the rolling mechanism in the current print layer is reduced by 20% to 50%.

[0069] As mentioned above, the travel speed of the rolling mechanism 400 is reduced every few printing layers, which can ensure that the rolling mechanism 400 can fully roll the printing layer, which is beneficial to improving the density of the embryo S. When executing this process step, the pressure of the rolling mechanism 400 can be increased at the same time to fully compact the embryo S.

[0070] According to the different materials, the printing parameters and drying temperature need to be adjusted to adapt to the material properties. For the above-mentioned materials, aluminum oxide, yttrium oxide, zirconium oxide, calcium oxide or silicon powder, preferably, the thickness of each printed layer is 5-200 microns, and the drying temperature is 50-200° C. This can ensure that a good embryo S is formed after printing by this printing method.

[0071] In some embodiments, when executing step S1, a plurality of printed layers are processed in sections according to the size of the structural strength along the Z-axis direction, and the initial value of the rolling pressure is adjusted according to the strength of the section structure.

[0072] As mentioned above, there are some casting components that are wide at the top and bottom but narrow in the middle. If the pressure is increased progressively, the embryo S will be damaged. For special components such as Figure 5 As shown, it can be divided into the upper part a, the middle part b and the lower part c. The upper part a and the lower part c are wide, while the middle part b is narrow. At this time, when rolling the lower part c and the middle part b, a pressure progressive rolling method can be used. When rolling the upper part a, the pressure can be adaptively reduced to only keep the current printing layer flat. In this way, the area is divided according to the structural strength of the casting, and the initial pressure value is appropriately adjusted to avoid damage to the embryo S during the molding process.

[0073] The following are embodiments and comparative examples of the present technical solution:

[0074] Example 1

[0075] This embodiment provides a 3DP synchronous micro-rolling printing method, which uses the above-mentioned printer, and the forming method includes the following steps:

[0076] Step 1: Select alumina powder with a particle size of 1000 mesh as the molding material and select phenolic resin as the binder;

[0077] Step 2: According to the size of the mold, a 3D model is established through 3D modeling software, and the 3D model is sliced ​​along the Z axis using slicing software to obtain several printing layers, and processing instructions are generated for all printing layers to set printing parameters and rolling mechanism parameters;

[0078] Step 3: Lay a layer of modeling material powder in the powder bed of the printer and compact the modeling material powder with a roller mechanism;

[0079] Step 4: During the compaction process, according to the processing instructions of the printing layer, the nozzle is used to synchronously spray the binder on the selected area above the modeling material powder layer, so that the modeling material powder layer is bonded to form the current printing layer contour, and then the nozzle returns to the starting position;

[0080] Step 5: When the nozzle returns to the starting position, a rolling mechanism is used to roll the printed layer synchronously along the XY plane. During the rolling process, the rolling pressure is 20N, the rolling speed is 100mm / s, and then the rolling mechanism returns to the starting position;

[0081] Step 6: The powder bed of the printer moves down one layer thickness along the Z axis, and the printer switches to the processing instructions for the next layer, which has a layer thickness of 100 microns;

[0082] Step 7: Repeat steps S2 to S5 in sequence, and increase the rolling pressure of the rolling mechanism as the number of printed layers increases, and increase the rolling pressure by 0.5N for every 10 layers printed, until the casting blank is formed;

[0083] Step 8: Take the embryo out of the powder bed and dry and solidify it to obtain the finished product. The drying temperature is 200°C.

[0084] The finished product prepared in the above embodiment has a surface roughness of 12.7±1.3 μm and a density of 3.04 g / cm 3 , porosity is 17%, shrinkage is 6%, and flexural strength is 41MPa.

[0085] Example 2

[0086] The difference between this embodiment and embodiment 1 is that in step S4, the pressure of the rolling mechanism is constant.

[0087] The finished product prepared in the above embodiment has a surface roughness of 15.5±2.2μm and a density of 2.78g / cm 3 , porosity is 23%, shrinkage is 9%, and flexural strength is 37MPa.

[0088] Example 3

[0089] The difference between this embodiment and embodiment 1 is that in step 7, while increasing the pressure of the rolling mechanism, the rolling speed of the rolling mechanism during printing of the current printing layer is reduced by 20%.

[0090] The finished product prepared in the above embodiment has a surface roughness of 11.5±1.1 μm and a density of 3.11 g / cm 3 , porosity is 15%, shrinkage is 5%, and flexural strength is 43MPa.

[0091] Comparative Example 1:

[0092] The difference between this comparative example and Example 1 is that the rolling mechanism in step S2 is not performed to compact the material powder.

[0093] The finished product prepared in the above comparative example has a surface roughness of 25.1±4.2μm and a density of 1.92g / cm 3 , porosity is 46%, shrinkage is 21%, and flexural strength is 28MPa.

[0094] Comparative Example 2:

[0095] The difference between this comparative example and Example 1 is that the rolling mechanism in step S4 is not performed to roll the printed layer.

[0096] The finished product prepared in the above comparative example has a surface roughness of 20.3±5.2μm and a density of 2.15g / cm 3 , porosity is 39%, shrinkage is 17%, and flexural strength is 31MPa.

[0097] The following is a comparison table of parameters of finished products prepared in the examples and comparative examples.

[0098]

[0099] It can be seen from the above experimental data that, in the embodiments and comparative examples, the comprehensive performance comparison of the printed parts is: embodiment 3> embodiment 1> embodiment 2> comparative example 2> comparative example 1, among which embodiment 3 is the best.

[0100] The finished product prepared by Example 3 adopts a rolling process at the same time, and the rolling pressure is adaptively increased and the rolling speed is reduced during the processing. Therefore, both the material powder before processing and the embryo after spraying the adhesive have good density. This makes the finished casting excellent in surface roughness, density, porosity, shrinkage rate and bending strength, which is beneficial to ensure the performance of the casting.

[0101] Example 1 does not use a printing method that reduces the roller speed. It can be seen that the finished product prepared by simply increasing the roller pressure does not perform as well as Example 3 in which the roller speed is simultaneously reduced.

[0102] The finished product prepared in Example 2, where the rolling pressure remains unchanged, performs worse than the finished products prepared in Examples 1 and 3.

[0103] Comparative Examples 1 and 2 reduce the rolling process compared to the present technical solution. By comparing Comparative Examples 1 and 2, it can be seen that the performance of the finished product prepared by a single rolling printing layer is better than that of the single rolling material powder.

[0104] In this technical solution, the above parameters are obtained by the following measures.

[0105] Measurement method:

[0106] ① Precision analysis (shrinkage rate): Use a digital vernier caliper with an accuracy of 0.01 mm to measure the dimensions of the sample along the X-axis, Y-axis, and Z-axis. The basic dimensions of the sample are 80 mm × 8 mm × 6 mm.

[0107] L=(l 1 -l 2 ) / l 1 ×100% (1)

[0108] Where L is the linear shrinkage, l 1 is the initial size, l 2 The dimensions are after drying.

[0109] ②Surface roughness analysis: Surface roughness was analyzed by a surface profile comprehensive measuring instrument. All samples were measured three times on the same surface.

[0110] ③ Porosity and relative density: The relative density of the sample is measured using the Archimedean principle, and 3 samples of each sample are selected to obtain the average value. The test process first uses a precision balance to measure the mass M of the dry sample. 1 and record; then suspend the same dry sample with a thin line and immerse it in water, and record the mass M of the water-saturated sample in water 2 and the mass M of the water-saturated sample in air 3 .

[0111] P=(M 3 -M 1 ) / ( M 3 -M 2 )×100% (2)

[0112] ρ 2 =M 1 ×ρ 1 / ( M 3 -M 2 ) (3)

[0113] Where: P is the porosity of the sample, ρ 1 is the density of water at 20°C (0.99 g / cm3), ρ 2 is the bulk density.

[0114] ④ Mechanical properties analysis (bending strength): The three-point bending strength was measured on a universal material testing machine at a loading rate of 5 mm / min. The span was 30 mm and the punch displacement speed was 0.05 mm / min. The three-point bending strength of the sample was calculated using force and displacement data.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for 3DP synchronous micro-rolling printing, Features: The steps include: S1. According to the size of the mold, a three-dimensional model is established by using a three-dimensional modeling software, and the three-dimensional model is sliced ​​along the Z-axis direction by using a slicing software to obtain a number of printing layers, and processing instructions are generated for all printing layers, and printing parameters and rolling mechanism parameters are set at the same time; S2, laying a layer of modeling material powder in the powder bed of the printer, and compacting the modeling material powder along the XY plane with a roller mechanism; S3. During the compaction process, according to the processing instructions of the printing layer, the nozzle is used to synchronously spray the binder on the selected area above the modeling material powder layer, so that the modeling material powder layer is bonded to form the current printing layer contour, and then the nozzle returns to the starting position; S4, when the nozzle returns to the starting position, the printing layer is synchronously rolled along the XY plane by a rolling mechanism, and then the rolling mechanism returns to the starting position; S5, the powder bed of the printer moves down one layer thickness along the Z axis direction, and the printer switches to the processing instructions for the next layer; S6, repeating steps S2 to S5 in sequence, and increasing the rolling pressure of the rolling mechanism as the number of printed layers increases, until the casting blank is formed; S7, taking the embryo out of the powder bed and drying and curing it.

2. The method for 3DP synchronous micro-rolling printing as claimed in claim 1, Features: The modeling material powder is one of aluminum oxide, yttrium oxide, zirconium oxide, calcium oxide and silicon powder with a particle size of 50-2000 meshes.

3. The method for 3DP synchronous micro-rolling printing as claimed in claim 2, Features: The binder is one of phenolic resin, furan resin, silica sol and yttrium sol.

4. The method for 3DP synchronous micro-rolling printing as claimed in claim 3, Features: The thickness of the printed layer is 5-200 microns, and the drying temperature is 50-200°C.

5. The method for 3DP synchronous micro-rolling printing according to any one of claims 1 to 4, Features: In step S1, a plurality of printed layers are processed in sections according to the size of the structural strength along the Z-axis direction, and the initial value of the rolling pressure is adjusted according to the strength of the section structure.

6. The method for 3DP synchronous micro-rolling printing as claimed in claim 5, Features: The rolling pressure range of the rolling mechanism is 1~2000N. For every N layers printed, the rolling pressure increases by 0.1~20N, 5≤N≤20, and the rolling pressure of the rolling mechanism in the last printed layer is ≤2000N.

7. The method for 3DP synchronous micro-rolling printing as claimed in claim 5, Features: When the rolling mechanism rolls a printing layer that is a multiple of N, the rolling pressure is increased by 0.1-20N, 5≤N≤20. When printing a printing layer that is not a multiple of N, the rolling pressure is the initial value.

8. The method for 3DP synchronous micro-rolling printing as claimed in claim 7, Features: When the rolling mechanism rolls a printing layer that is a multiple of N, the rolling travel speed of the rolling mechanism in the current printing layer is reduced by 20% to 50%.

9. Application of the 3DP synchronous micro-rolling printing method as described in any one of claims 1 to 8 in a casting mold.

10. A printer used in the 3DP synchronous micro-rolling printing method as claimed in any one of claims 1 to 8, comprising a first displacement mechanism, a carrier, a powder distribution mechanism, a rolling mechanism, a second displacement mechanism, a nozzle and a powder bed, in, The first displacement mechanism and the second displacement mechanism are three-axis screw slides; The carrier is arranged on the first displacement mechanism; The powder distribution mechanism, the rolling mechanism and the second displacement mechanism are each connected to a linear displacement component and are sequentially arranged in parallel on the carrier; The nozzle is arranged on the second displacement mechanism; The powder bed is arranged on one side of the first displacement mechanism, and the bed surface of the powder bed faces the powder distribution mechanism, the rolling mechanism and the nozzle.

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